1. Field of the Invention
The present invention relates to apparatus and method for reproducing video signals that is suited for decoding and reproducing video signals that are recorded being compressed by, for example, a moving picture coding experts group (hereinafter abbreviated as MPEG) system. More specifically, the invention is for favorably reproducing and displaying the video signals in reproducing the recording medium recorded by the MPEG system at the time of a high-speed search, etc.
2. Description of the Related Art
In an apparatus and method for reproducing video signals by decoding and reproducing the video signals that are recorded in a compressed manner by, for example, the MPEG system, it is an accepted practice to decode a frame called I-frame that is provided, for example, every after 15 frames of video signals and that can be decoded by itself. By using the thus decoded I-frame, frames called P- and B-frames formed by the differences among the frames are decoded to reproduce all frames forming the video signals.
When the recording medium recorded by the MPEG system is to be reproduced by a time series such as a high-speed search which is different from that of during the recording, the I-frames that can be decoded by themselves only are decoded successively to form video signals. That is, when, for example, the I-frame is provided every after 15 frames as described above, the I-frames only are reproduced in the high-speed search at a speed 15 times as fast.
In practice, however, a time is required for detecting the I-frames based upon the addresses added to the frames, and only, for example, about 3 to 5 frames can be reproduced in a second. In the conventional device, therefore, the video signals have been intermittently updated and fetched in a unit of a frame for every predetermined period of time by repeating the preceding frame in a period in which, for example, 3 to 5 frames are reproduced in a second.
According to the above method of intermittently updating and fetching the video signals in a unit of a frame for every predetermined period of time, however, the video signals that are displayed produce a very unnatural display. That is, when, for example, 5 frames are displayed a second at a speed of 15 times as fast, the frames that are displayed are each every after 90 frames. Therefore, the interval among the frames that are displayed is three seconds in the standard time of reproduction, which is longer than an interval of, for example, 0.5 seconds in the analog-type VTR, and becomes unnatural.
Further, when, for example, 5 frames are displayed a second, the time for displaying each frame is 0.2 seconds, which is long enough for the viewer to perceive the picture of each frame to a sufficient degree. Therefore, the display in which the thus perceived picture is intermittently updated appears very unnatural to the viewer compared with the display in which the pictures that cannot be fully perceived appear continuously such as in the high-speed search of the existing analog VTR.